Appropriations bill: What Congress actually spends. Congress has the purse and the purse strings. This will track the budget in some areas, but not in all areas. This is signed into law.
By Congressional protocol, each Congressional committee has its own appropriations bill, resulting in 12 separate spending bills being considered, per year.
Omnibus Appropriations: Combining multiple appropriations bills into one appropriations bill, with the typical arrangement being all 12 (omni) in one spending bill.
Thank you, Cboldt—Well done.